ES2203973T3 - TWO COMPONENT THIXOTROPIC POLYURETHANE SYSTEMS. - Google Patents

Abstract

The invention relates to two-component polyurethane systems, consisting of one polyol component and one isocyanate component. Said polyol component contains at least two amines A1 and A2, the reactivity R1 of amine A1 with isocyanate being considerably greater than the reactivity R2 of amine A2 with isocyanate. As a result, two time-delayed reactions take place. This gives the inventive systems the desired low level of viscosity, and the thixotropic properties which prevent even thick layers from sliding off of vertical surfaces. The inventive two-component polyurethane systems can be used for producing cubing models, master models and similar in the automobile industry and for producing structured bodies and thick films and sealing beads.

Description

Two-thixotropic polyurethane systems components.

The present invention relates to systems of Two component thixotropic polyurethane, to one procedure for its manufacture and its use.

In many uses of polyurethane systems two components (PUR-2C), especially for the manufacture of molded parts for Cubing models, for prototypes, etc. of the car industry, it is desired that said two component systems immediately after mechanical mixing of the components and the application of the mixture have a thixotropic behavior, so that after the application on vertical surfaces, even in thick layers, Don't tend to hang up.

So far they have been used for this purpose pasty polyurethane systems, with filler loads, containing inorganic and / or organic thickeners incorporated by usually to the polyol component. It is also known as composition thixotropic coating a formulation of a binder and a reaction product of a diisocyanate with a primary polyamine or secondary, especially with benzylamine, which acts as sliding controller (patent DE-27 51 761). In thixotropic agents have also been described resins of polyamide with free amino groups, integrated into the resins of paint to form gels (EP-A-0006 252, p. 1).

It is also known that by reaction of primary and / or secondary polyamines, alcohols and / or monofunctional amines with diisocyanate compounds, urea adducts that are generated in situ with the binder or a part of the binder are obtained, said adducts are thixotropic (DE-patent 23 60 019).

In the document DE-A-40 23 005 systems are described thixotropic polyurethane, based on a polyol component and a isocyanate component, said polyol component contains a mixture of polyamidamine and low molecular weight polyfunctional amines, in Special aromatic amines. The mixture of the polyol components, Isocyanate and amine have for a short time the low viscosity that is needed for the application, after the application starts the thixotropy required for the application of the mixture on vertical walls or on surfaces located above the head (the the ceiling). In the execution examples, systems of polyurethane in layer thicknesses of 5 mm, which are used as adhesive systems eg for glazing. The systems of Polyurethane described in this German patent application use certainly a combination of two amines, but these amines react at the same time with the isocyanate, in order to achieve the desired effect in terms of low viscosity and thixotropy. To apply thicker layers (20 to 50 mm), these systems they are not adequate, since they cannot completely prevent the pick-up of these layers, due to the intense heat that is generated during the exothermic crosslinking reaction.

Based on these facts, the present invention it is proposed to develop two component polyurethane systems improved, whose components after mechanical mixing generate by chemical reaction in a very short time a sufficient thixotropy, that on the one hand give rise to the applied brushstrokes maintain a sufficient flexibility so that these can be integrated so enough in each other, and on the other hand enable the application of brushstrokes of large layer thicknesses on surfaces vertical, without their pick-up taking place when The exothermic crosslinking reaction is initiated.

The objective of the present invention is achieved. in the terms described in claim 1.

The advantages of the forms of execution of the The invention follows from the subsequent claims.

The invention further relates to a process. of manufacturing a polyurethane system (claim 12) and a its use (claim 13).

The advantageous features of the system PUR-2C of the invention are the following:

1. Liquid consistency of the two components initials, which allows easy mixing of the components.

2. Good extensibility of the different brush strokes that are applied, with their integration, of this so smooth surfaces and few air inclusions are obtained.

3. Good stability of the paint mass and, by this, little tendency to pick up when applied on vertical surfaces

4. Pot-life (or available time for the application) length, which allows to obtain smooth brushstrokes, and so on

5. Possibility of applying several successive layers, one over the other, with good anchoring between them.

6. Variable consistency at the time of application depending on the quantity and the tranche applied.

The polyurethane system of the present invention is based on a two component system (system PUR-2C) liquids. The resin component consists of polyether polyols and / or polyester polyols with portions of fillers filler, the crosslinking component is an isocyanate based on the 4,4'-diphenylmethane diisocyanate (MDI) of low viscosity and does not contain filler charges.

According to the invention, the most important thing is that the thixotropy of the system can be adjusted temporarily in such a way that, after mixing, the system in a first stage by reaction of the amine A1 with the isocyanate becomes thixotropic so that it moisturizes the substrate well and spreads well in the depressions or cavities covered by brush strokes, but at same time be stable enough to anchor well and do not pick up vertical walls even when applied in layer thicknesses of 20 mm or more. The structural viscosity, generated In this first stage, it is usually not enough to prevent pick-up of the applied layer after the reaction starts crosslinking between the polyol and the isocyanate, due to the heat of reaction that is released and the consequent weakening of intermolecular adhesion forces, therefore another reaction that starts with a certain time delay. Therefore, in a second stage generates a structural viscosity in the system or stronger thixotropy by reaction of amine A2 with the isocyanate, said thixotropy remains stable at temperature, but that, after the reaction, no longer allows leveling or extension that takes place in the first stage.

The modified polyol and isocyanate system of the invention therefore has to satisfy two requirements as far as to the application, the 1st task consists of a good humidification and good leveling or smoothness immediately after application on the substrate and good temperature stability not exceeding 40 ° C; the 2nd task consists of good adhesion intermolecular after the exothermic reaction of crosslinking between the polyol and the isocyanate and the consequent temperature increase, which can reach 80 ° C, thereby the removal of the applied layers even in thicknesses is prevented large on vertical surfaces.

Both requirements cannot be satisfied with the use of a single amine or of mixtures of amines that react to Same time. Increasing the amount of amine or choosing opportunely the types of amine can satisfy the 2nd requirement to prevent the removal of applied layers, but cannot meet the first requirement of good wetting and extension on the substrate. Now it has been found that both requirements can be met by employing at least two or more amines, which are clearly differentiated in terms of reactivity. The R1 reactivity of amine 1 with respect to the isocyanate component it has to be greater than the reactivity R2 of the amine 2 with respect to to said isocyanate component. It has been found according to the invention that the ratio of reactivities of amine 1 with isocyanate and of the amine 2 with the isocyanate, ie R1: R2, has to be located between 1000 and 5 and preferably between 100 and 5.

At time 0 the mechanics are mixed material components with each other. In the first stage, the amine 1 reacts in a few seconds with the isocyanate. The process of Extension is practically terminated. In the second stage, following the reaction of the first stage, the amine 2 reacts with the isocyanate in a period of 1 to 2 minutes and form a gel-like structure that stands by bridges of hydrogen and other intermolecular forces, so that during the "pot-life" (time available for application), in which the polyol reacts with the isocyanate, no longer any of the applied layer is lifted. The pot-life is 30-40 minutes, of no be by the reaction of amine 2, after about 20 minutes it would produce the removal of the layers applied on surfaces vertical

Among the amines 1, which are added to the component polyol and that are especially suitable for the first stage of reaction, the following amines are counted, whose reactivity R1 is > R2:

1a) aromatic amines, for example

2,4- or 2,6-toluylenediamine (ADD),

the 3,5-diethyl-toluylenediamine (DETDA),

the methylene-bis- (2,6-diisopropylaniline) (M-DIPA),

the methylene-bis- (2-methyl-6-isopropylamine) (M-MIPA),

the methylene-bis- (2,6-diethylaniline) (M-DEA),

the 4,4'-methylene-bis (6-methyl-aniline),

2,6-diisopropylaniline (DIPA),

the 2-methyl-6-isopropylamine (MY DAD),

the 4,4'-diamino-diphenyl-methane (MDA);

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1b) cycloaliphatic amines, for example

the 3-isocyanatomethyl-3,5,5-trimethylcyclohexylamine (isophoronadiamine, IPD),

the 4,4'-diamino-3,3'-dimethyl-cyclohexylmethane, Laromin C 260,

cyclohexanediamine,

the piperazine, the N-aminoethylpiperazine;

1c) araliphatic amines, for example

m-xylylenediamine (M-XDA) and derivatives

and other types provided with an amino group of aromatic and other aliphatic character;

1d) aliphatic amines and polyamines, for example

butylamine,

diethylenetriamine,

triethylenetetramine,

the trimethyl-hexamethylene diamine,

pentaethylenehexamine,

polyether polyamines such as H 2 N- (CH 2 -CH 2 -O) x -CH 2 -CH2 -NH2 and derivatives.

Between the amines 2, which are added to the component polyol and that are especially suitable for the second stage of reaction, the following amines are counted, whose reactivity R2 is <R1:

the methylene-bis (3-chloro-2,6-diethylaniline) (M-CDEA),

the 3,5-dimethylthio-2,4- or -2,6-toluylenediamine that can be purchased as Ethacure 300 commercial product from Ethyl Corp.,

the 3,5-diamino-4-chloro-benzoate of isobutyl (DACB),

the methylene-methyl bis-anthranilate (MBMA),

the 4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCA), etc.

Type A2 amines are very slow amines of reaction due to electron attraction effects or effect mesomers resulting from the decrease of basicity and / or of steric impediments The determining factor is that amine 2 has a reactivity clearly lower than amine 1 with respect to it isocyanate It is also possible to combine an amine 1 of the groups of 1b) to 1d) with an amine 2 of group 1a), assuming that in this combination exists a sufficient difference in terms of reactivity. Mixtures of amines of the different groups

A comparison of the relative reactivities of the amines of groups 1a), 1b) to d) and 2 are collected in the following table 1.

TABLE 1

Group amines Reactivity relative two from 0.1 to one 1st) from 5 to 200 1b), c), d) from 100 to> 1000

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In practice, this means that in the conditions mentioned in example 1 and 2, the amines of the groups from 1b) to 1d) react with the isocyanate immediately, the amines of group 1a) do so in a time of 5 to 10 seconds and group 2 amines need 30 to 90 seconds to do what.

The amino compounds mentioned above they can be mixed with the suitable polyols in the form of formulations liquid As polyols polyols are taken into consideration known for the chemistry of polyurethanes and that they possess so minus 2 alcoholic hydroxyl groups. They belong to this group the known linear or branched polyether polyols, whose weight molecular is between 75 and 6,000, described for example in DE-21 60 589 or DE-A-33 40 588. The components formulated polyol have a viscosity at 25 ° C comprised between 1,000 and 60,000 mPa \ cdots. They can be incorporated into the polyol component other ingredients, eg drying agents, pigments, dispersants, plasticizers, antifoam and event. catalysts Belong to they for example potassium-sodium alumosilicate Zeolite-type commercial (secant), chalk, calcium carbonate, pigments, hydrocarbon-based plasticizers and event. tertiary amines and organic tin compounds that act as catalysts

As an isocyanate component they are taken in consideration those that are suitable for use in systems PUR-2C and are described for example in the patent DE-21 60 589 or in DE-A-33 40 588. They are preferred in especially aromatic diisocyanates, for example those derived from 4,4'-diphenylmethane diisocyanate (MDI) and the Toluylene diisocyanate (TDI). The isocyanate component has a viscosity at 25 ° C from 10 to 10,000 mPa ·.

The stoichiometric ratio between the component polyol and all its additives and the isocyanate component can be between 100: 10 and 100: 200 parts by weight.

The amount of amine 1 in the polyol component it is between 0.25 and 5% by weight, preferably between 0.5 and 2% by weight. The amount of amine 2 in the polyol component it is between 0.3 and 5% by weight, preferably between 1 and 2% by weight. To achieve the desired effects, the adding a combination of amine 1 with amine 2 in one 0.5: 1 to 2: 1 ratio (% by weight), for example in a proportion 1.5: 1.5% by weight.

To the polyol component the amines of the invention before the reaction with the isocyanate component. The polyol component and all the additives it carries are mixed mechanically with the isocyanate component before carrying out the application on the desired substrate.

The invention is illustrated in greater detail. through the execution examples.

Example 1

The heat dissolves 4,4'-methylene-bis- (3-chloro-2,6-diethylaniline)  (M-CDEA), m.p. 85 ° C, eg that sold by the Lonza AG of Basel, as an amine 2, in the component polyether polyol As polyol 1, a polypropylene glycol of a hydroxyl number of 380 mg KOH / g and a viscosity at 25 ° C of 650 mPa.cots. They are added to the solution the other components, that is secant 1, which is a commercial K-Na alumosilicate of the zeolite type A and it is marketed eg by Bayer AG of Leverkusen under the name of Baylith L Powder; as a catalyst diazabicyclooctane, which in the form of a 33% solution in dipropylene glycol is marketed eg by the company Biesterfeld & Co., Hamburg, with the name of Dabco 33 LV; calcium carbonate that is marketed in the form of Crete eg by the company Omya, Cologne, with the name of Omya BLR two; and the 4,4'-diamino-3,3'-dimethylcyclohexylmethane (Laromin C 260 from BASF, Ludwigshafen) as an amine one; and incorporated and dispersed by a disk agitator jagged. The total mixture is subjected to vacuum to degas.

polyol one 100g amina 2 6 g secant 1 fifteen g catalyst 0.05 g calcium carbonate, crete 285 g amina 1 6 g mix viscosity approx. 25 Pa.s mix density approx. 1.8 kg / l

The mixture prepared in this way is mixed in one usual 2 component mixing and dosing machine with the 4,4'-diphenylmethane diisocyanate modified with prepolymer, density 1.23 kg / l, NCO content of 28%, 250 mPa viscosity at 25 ° C, as isocyanate 1, in a stoichiometric ratio of 100: 30 parts by weight. Is obtained a thixotropic mass that can be applied in a single operation by a flexible tube on vertical surfaces with a thickness of layer of 20 mm or more and that reticulates giving rise to a material rigid, whose Shore D hardness is 90.

Example 2

The heat dissolves 4,4'-methylene-bis- (3-chloro-2,6-diethylaniline)  (M-CDEA), m.p. 85 ° C, eg that sold by the Lonza AG of Basel, as an amine 2, in the component polyether polyol As a polyol 2, a polypropylene glycol with a hydroxyl number of 76 mg KOH / g and a viscosity at 25 ° C of 900 mPa.cots. They are added to the solution and they are mix the other components with agitator, that is secant 2, which is a zeolite paste formulation in castor oil and it marketed for example by Bayer AG of Leverkusen under the name of Baylith L Pasta; butanediol-1,4; as diazabicyclooctane catalyst, which in the form of a 33% solution in dipropylene glycol it is marketed eg by the company Biesterfeld & Co., Hamburg, with the name of Dabco 33 LV; and the 4,4'-diamino-3,3'-dimethylcyclohexylmethane (Laromin C 260 from BASF, Ludwigshafen) as an amine one.

polyol two 100g amina 2 1.3 g secant 2 12 g butanediol-1,4 9 g catalyst 0.05 g calcium carbonate, crete 285 g amina 1 1.8 g mix viscosity 1.3 Pa.s a 25ºC mix density 1.05 kg / l

The mixture prepared in this way is mixed in one usual 2 component mixing and dosing machine with the aromatic diisocyanate modified with prepolymer, density 1.21 kg / l, NCO content of 25%, viscosity at 25 ° C of 300 mPa •, as isocyanate 2, in a proportion Stoichiometric 100: 60 parts by weight. You get a dough thixotropic that can be applied in a single operation using a flexible tube on vertical surfaces with a layer thickness of 20 mm or more and which reticulate giving rise to a rigid material, whose Shore A hardness is 90.

Claims (11)

1. Two component polyurethane systems, consisting of a polyol component and an isocyanate component, characterized in that the polyol component contains at least two amines A1 and A2, the amount of at least one amine A1 in the polyol component is situated between 0.25 and 2% by weight and the amount of at least one A2 amine in the polyol component is between 0.3 and 2% by weight, the reactivity R1 of at least one amine A1 with with respect to the isocyanate component it is greater by a factor of 5 to 1,000 than the R2 reactivity of at least one A2 amine with respect to the same isocyanate component and the reactivity of the polyol component with respect to the same isocyanate component is less than the R1 and R2 reactivities of amines A1 and A2, respectively. 2. Two component polyurethane system according to claim 1, characterized in that the ratio between the reactivity R1 of the amine A1 and the reactivity R2 of the amine A2 with respect to the isocyanate component is between 1,000 and 5. 3. Two component polyurethane system according to claim 1, characterized in that the ratio between the reactivity R1 of the amine A1 and the reactivity R2 of the amine A2 with respect to the isocyanate component is between 100 and 5. 4. Two component polyurethane system according to one of the preceding claims, characterized in that the amine A1 is chosen from aromatic amines (group 1a), cycloaliphatic amines (group 1b), araliphatic amines (group 1c) and / or aliphatic amines and aliphatic polyamines (group 1d). 5. Two component polyurethane system according to one of the preceding claims, characterized in that the amine A2 is selected from group 2, which comprises: the methylene-bis (3-chloro-2,6-diethylaniline) (M-CDEA), the 3,5-dimethylthio-2,4- or -2,6-toluylenediamine, the 3,5-diamino-4-chloro-benzoate of isobutyl (DACB), the methylene-methyl bis-anthranilate (MBMA), the 4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCHA). 6. Two component polyurethane system according to claim 4, characterized in that the amine A1 is chosen from the groups 1b), 1c) and / or 1d) and that the amine A2 is chosen from the group 1a), the reactivity R1 of the amine A1 chosen from groups 1b), 1c) and / or 1d) greater than the reactivity R2 of the amine A2 chosen from group 1a). 7. Two-component polyurethane system according to one of the preceding claims, characterized in that the amine A1 is 4,4'-diamino-3,3'-dimethyl-cyclohexylmethane and the amine A2 is 4,4'-methylene- bis- (3-chloro-2,6-diethylaniline). 8. Two component polyurethane system according to one of the preceding claims, characterized in that the weight ratio between amine A1 and amine A2 is between 0.5: 1 and 2: 1 in% by weight. 9. Two component polyurethane system according to one of the preceding claims, characterized in that the polyol consists of polyether polyols and / or polyester polyols of a molecular weight between 75 and 6,000 and the diisocyanate is a derivative of the 4,4'-diphenylmethane diisocyanate . 10. Process for manufacturing a two-component polyurethane system according to one of the preceding claims, characterized in that an amine component is dissolved in the polyol component, the second amine component and the desired additives are dosed and added with a stirrer and the The resulting mixture is mixed with the diisocyanate in a mixing or dosing machine. 11. Use of a two polyurethane system components according to one of claims 1 to 9 for the manufacture of molded parts for Cubing models, for prototypes, etc. of the automobile industry as well as for the manufacture of structured objects and thick layer paints and also of sealing cords.